


Polonium

by 7PercentSolution



Series: Periodic Tales [10]
Category: Sherlock (TV)
Genre: Autistic Sherlock, Chemistry, Doctor John Watson, Gen, Kidlock, Murder, Mycroft's Umbrella, Radioactive, Sherlock is climbing the walls, giving up smoking, nicotine addiction
Language: English
Status: Completed
Published: 2016-08-15
Updated: 2016-08-15
Packaged: 2018-08-08 23:07:20
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 14,055
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7777255
Author URL: https://archiveofourown.org/users/7PercentSolution/pseuds/7PercentSolution
Summary: <blockquote class="userstuff">
              <p>One of the deadliest substances known to man, polonium is a trillion times more toxic than hydrogen cyanide. Polonium is so radioactive that a solid lump of its most common isotope- Polnium210- will glow due to the excitation of the air around it. As such, Sherlock would be irresistibly drawn to it.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> Po 84 atomic weight 209
> 
> Part One: Polonium is an extremely rare semi-metal. It is reactive, silvery-gray, and it dissolves in dilute acids, but it is only slightly soluble in alkalis. It is fairly volatile, with a short half-life. It is easily dispersed into air- about half of a sample of it will evaporate within 3 days, unless it is kept in a sealed container.

"How are you doing in there?"

She put the whispered question gently, but she could see that it worried Sherlock nevertheless. He was trying not to fidget, but she saw the briefest flash of discomfort work its way into his eyes.

"The shirt itches, the jacket is too warm, the tie is…ridiculous-why do people put up with these things? The sun through that window is too bright in my eyes, the place reeks of wood polish and I would really rather be home right now."

It all came tumbling out at his usual breakneck speed, even if it was whispered. But, Esther Cohen was grateful for that. _At least he's talking_. She had worried that the 'pre-selection interview day' at Harrow would just prove to be too much and he'd retreat into silence. She'd worked too hard at making this happen, and she didn't want it to go wrong, for his sake. Of course, Mycroft had made it clear to his brother. _Too clear- he scared Sherlock half to death._

"You need to take this seriously, Sherlock." Even 8,000 kilometres away and over a bad telephone line, Mycroft's voice carried weight and authority. "This is a one-and-only chance. You have to _act_ normally, within acceptable bounds of behaviour. Lord knows, you've been taught enough of that by Mummy and your tutors. Now's the time to deliver the necessary performance. It's the only way you'll be able to avoid Father sending you off somewhere horrible. So, just…do it. I know you can, but it's time for you to prove to everyone else that you can, too, when it really matters."

Sherlock had been quiet, almost subdued into silence when she collected him this morning from the South Eaton Place townhouse. She spent the forty minute drive through north London's rush-hour traffic on last minute coaching and trying to get him animated. "So, Sherlock; the house master is almost certain to ask you why you want to go to Harrow. What are you going to say?"

The reply came back though slightly clenched jaw. "Because if I don't get into Harrow, Father will send me to a special needs school where I will be locked in, and then my brain will just shrivel up with boredom and I will want to die."

She sighed. "Not the answer I was looking for, Sherlock, and certainly not the one that will get you into Harrow. So, let's try this one again. Think of what they _want_ to hear from you." The rest of the journey was spent polishing the rough edges off his reply.

Upon arrival at Harrow, it was straight into a computer-based intelligence test, and a composition writing test. Then they'd gone on a brief tour, which seemed to help settle him. They were now sitting in a small anteroom at Bradby's House*, waiting for the interview with the House Master. She tried to still her own nerves, hoping she would be able to mask her worries from those perceptive grey-green eyes. _He looks fine on paper, but can he pull it off when he's face-to-face?_

"Master Goodison will see you now, young man." The secretary at Bradby's was experienced at dealing with applicants. She kept her voice kindly. She'd seen boys pass out, burst into tears and once, literally run out of the room screaming. The interview was a nerve-wracking experience when so much of parents' expectations were riding on this one half-hour conversation.

Esther watched him go in. _Good luck, Sherlock._

Geoffrey Goodison was a tall, thin, ascetic looking man, with dark hair and piercing eyes. He was standing and offered to shake hands with the thirteen year old, who hesitantly complied, with a not-too-hard, not-too-limp grip. The House Master thought, _He's practiced that enough times to get it right._ He gestured the boy into a hard-backed wooden chair in front of the desk and took his own seat behind the desk.

"You know it is unusual for Harrow to take an applicant this late. We only reserve seven places each year for late entry, across the whole school. This year I can only take one into Bradby's"

Sherlock nodded, as if not trusting his own voice.

"But, then _you_ are unusual, and your circumstances are, too."

Again, the young boy nodded. His eyes were wandering about the study rather than looking at Goodison.

"So, Mister Holmes, tell me why you want to come to Harrow."

The boy seemed to hesitate. And then he raised his chin and said almost defiantly, "I've just seen your Chemistry labs; that's why I want to come here. They're BRILLIANT." The last word came out with a barely suppressed sigh of delight. "I'll be able to do experiments that I haven't been able to do at home…" Then as an afterthought, the boy pulled his eyes to the House Master's own and said belatedly, "…sir."

 _Doesn't like eye contact, but he'll do it because he's been told to do so, like that handshake._ The House Master was used to boys being coached. He sometimes felt that the interview had become more a test of a boy's acting abilities more than a revelation of their true character. The last three late applicants he'd seen were certainly producing Oscar winning performances, probably because they'd failed their entrance interview at other public schools. As House Master, his job was to probe what was underneath the polished answers, to ask the unexpected, something that couldn't be predicted in advance, create a chance to see beyond the prepared speeches. This boy's answer wasn't polished, wasn't coached; it reeked of the truth.

Goodison had reviewed the boy's application, and the detailed reports from each of his tutors. Their praise was extraordinary, but then as educators paid by the boy's family to deliver the one-to-one tutoring of a boy schooled at home, their views could be …over-inflated, as a matter of self-interest. Parents who paid for that kind of teaching wanted to hear only the best. He needed to figure out the truth in the next thirty minutes. Certainly the intelligence test scores, already generated and on his desk while the boy was on the tour, boded well. They were the highest he'd seen in years. He scanned the boy's personal statement. A lot of it was about chemistry.

"You like chemistry, don't you?"

"Like?" A frown of confusion passed over the boy's face. "No, _like_ doesn't begin to explain it."

That made Goodison smile. "Then explain it to me, please."

The boy looked down at his hands. "Chemistry is life. All life. It's how things become alive, and how when they die they revert to their basic elements again. It's about entropy and energy and how everything everywhere is connected. Everything else I've studied, well, if it helps explain the chemistry, then that makes it worth studying. I need advanced maths to work the equations, and physics to understand what is happening at the atomic level. But, the best thing is that chemistry doesn't _lie_. It's the essence of _everything_. The more I learn, the more there is to learn. I'm never _bored_ with chemistry."

There was a passion and an intensity in the delivery of this soliloquy that made Goodison realise that he'd hit truth again. He decided to probe more; he needed to know how the boy's mind worked. "Tell me now what experiment you'd most like to do, if you could do anything at all."

"I'd like to find out why there's polonium 210 in cigarette smoke."

Goodison wasn't a chemist. He had a vague recollection that polonium was a radioactive element, but the idea that such a thing as found in cigarette smoke just sounded… preposterous.

"Is there?" it was a direct challenge. How would the boy take it?

Holmes tilted his head to the side a bit. There was a pause, when Goodison could see the war going on. Should he answer politely, or should he take up the challenge?

A little huff of breath, and then he was off. "Of _course,_ there's polonium in cigarette smoke. That's been known since the 1960s, along with arsenic and cyanide, and other carcinogenic ingredients. But, the tobacco companies haven't exactly been shouting the results, have they? For obvious reasons, so if you haven't heard of it, then you aren't a chemist or a doctor. The scientific journals have the evidence though. Do you smoke?"

Goodison smiled again at the abruptness of the question. "Yes, occasionally. Have you tried it? Why are you interested in what's in it?"

Sherlock screwed up his face in disgust. "I couldn't smoke- the smell alone is revolting. My Father smokes. In part I want to know if the polonium will kill him, but really I want to know if it's a better way to produce polonium."

"What would you actually _do_ in your experiment to test that?"

Sherlock looked uncomfortable, and his left thumb was rubbing his index finger fiercely. "Um, would you mind if I stood up? It will help me answer the question…sir"

It was unorthodox, but Goodison nodded; the boy was out of his seat in a flash and pacing.

"Polonium was first discovered by the Curies in 1898, but they needed to process over a tonne of pitchblend to yield a tiny amount of the element, just a hundred micrograms. If I could find a way to harvest it from cigarette smoke that would be a bit amazing. People make polonium now by blasting bismuth with neutrons. That takes energy. Tobacco leaves seem to accumulate the ingredients needed- don't know how, that's worth exploring in its own right. The hairy underside of the leaves seems to collect the raw materials from the atmosphere and soils. But what is _really_ interesting is how that all comes together in the process of combustion through oxygen inhalation in the cigarette. Polonium is produced- but _how_? Would it work the same if the cigarette was much bigger- say the size of a brick? Is it because the tobacco is cured? Does that intensify the presence by driving off the water and other liquids? Is it because it is shredded? Would a brick-sized pile of tobacco leaves produce as much or more polonium if it was 'smoked'? It would be fun to design a machine to do _that_. And does it actually have to involve inhalation- which is after all just an intensification of oxygen flow? If you set a whole barn of fresh tobacco leaves on fire would it generate as much polonium? There are just so many directions to study." He paused to take a breath.

"You aren't interested in stopping people from smoking?" Goodison couldn't resist throwing a little grit into the machinery to see how the boy dealt with it.

The pacing stopped, and the head tilt reappeared. "Why would I want to do that?"

"Because saving lives is important?" The House Master volunteered this to see if the boy would revert to the coached approach to challenge. Almost everyone knew that one of the interview questions would be on ethics. It was an old standby for public school interviews.

"That's for other people, doctors and the like." The boy waved a thin bony hand in dismissal, and resumed pacing. "I'm interested in the _chemistry_. Having a sustainable, renewable source of polonium is really interesting. Instead of using tobacco to _kill_ people through cancers…" here he looked pointedly over at the House Master, "why not harvest it as a source of a precious element? Only a hundred grams of polonium are manufactured a year- _in the whole world_. If there was more of it, then it could be used in scientific work that's _really_ important."

Intrigued, Goodison tilted back in his chair, "Such as?"

The boy put his hands on the back of the chair in front of the desk, as if grounding himself. "Polonium 210 is an important source of neutrons. It's usually put together with beryllium, where the alpha particle emitted by the radioactive polonium helps in release of neutrons from beryllium. If that isn't enough, a small amount of polonium releases a large amount of energy every second in the form of alpha particles."

He clearly thought that was enough explanation. Goodison pursed his lips, and decided to call the boy's bluff, if it was one. "So what?"

That provoked a frown and undisguised criticism in the tone of the boy's reply. "If the pure science isn't good enough for you, sir, then think of the applications! It could be used in thermoelectric cells and in isotope thermoelectric generators, because that converts the energy released by the radioactive decay of an element into electricity. Think of space exploration; it could be driven by polonium if it was readily accessible and renewable through on-board hydroponics." The boy's direct eye contact was now directly challenging the House Master to realise the importance of his statement.

Caught up by the lad's enthusiasm, Goodison had to smile. _Time to bring this back down to earth._

"You'd best sit down, Holmes. Harrow is much more than a chemistry lab. What about sport, the arts, music? What do you like doing when you aren't studying?"

The boy took his seat again, and stilled. "I play the violin."

Goodison tried to recall that fact from the application. "To what level?"

"ABRSM Level Seven distinction, sir."

For a thirteen year old, that was a significant talent. "Shame you couldn't have applied for a music scholarship here, but the auditions happened in February. Why do you like the violin- that is, assuming you do, and aren't just doing this to satisfy your parents."

"My mother taught me, to start with, but then she died. Father doesn't care. He only listens to my brother's piano playing."

"That doesn't answer the question."

"I like the violin because it's true. Music is like maths. If you can master the bowing technique and the fingering, then the sound is…perfect. I have a good ear, perfect pitch. And, like chemistry, if you put the basics together, you get something interesting. I _like_ doing that. I like to experiment with it, write my own music."

As much as he was enjoying the conversation, it was time now for Goodison to focus on the principal question mark over this applicant. "You've been home schooled all your life. Not much contact then with boys your own age or older. There are a _LOT_ of boys here at Harrow and a good deal of education here is about how to get on with each other. How do you think you'll do?" It wasn't meant as a trick question. He assumed the boy would have been coached in how to talk up his extra-curricular activities, his sociability. What came out was again blunt but honest.

"I don't know. I've not had a lot of experience with it. What I have had, with village boys near home, I didn't like much."

"Why?"

"Because they're stupid." He blurted it out, then went a bit pink, when he realised that it was far off line from what Esther Cohen had told him to say.

"Well, that's honest. But it won't endear others to you. Tell me about a friend of yours. What makes him a friend?"

"I don't have friends, at least not the way they write about friends in books."

"Why not?"

"I get bored with other people. I'm better on my own."

Goodison took a stern tone. "We don't often get that chance in life, Holmes. You need to learn how to get on with others- even the boring ones. A lot of Harrow's life involves activity outside of the classroom and we require you to learn teamwork and get on with others. It's important. If you don't want that, then Harrow is not for you."

"I know that I will have to get on with others. If the price of being here and using that lab is to learn how to deal with other people, then I will do it. That's what a school is for- to teach me what I don't know I need, in order to get what I want. That's why I'm here."

Goodison thought about that answer for a moment. Brutally transactional, not exactly orthodox. But, it was a basis on which he could work. And at least it was honest. He got up, walked to the door, and popped his head out. He asked "Would you like to join us now, Doctor Cohen?"

When the petite dark haired woman was seated, the House Master gave her a reassuring smile. "As you know, this is a late application, and an unusual one. Normally, at thirteen we'd expect a candidate to take the Common Entrance Exam, or the Common Academic Scholarship exams before applying. But Sherlock's GSCEs are a more than acceptable alternative in the seven subjects he took. In theory, his six As and a B would be good enough to get him into the Sixth Form here. But those boys are seventeen and eighteen years old. If he's going to get the best out of Harrow, then he will have to start as a shell* in September. We can adjust his academic work to the highest sets or a higher form where needed, but he will have to fit in with his age group for the rest of college life."

Esther tried to keep her delight off her face. And then a worry reappeared. "Is there any possibility of his coming into Bradby's _this_ term? His home situation requires a move into boarding in the next two weeks."

Having made the decision, the House Master now realised that this boy was going to be a high maintenance choice. But, he thought it was worth it, just occasionally, to have a boy who wasn't so interested in having a posh public school name attached to his own. Holmes couldn't care less about Harrow's history, but that didn't matter. And if he wanted to start a term before the other new boys arrived, well, that could be accommodated. He decided to put Doctor Cohen out of her misery. She was clearly worried.

"It's unusual, but not unheard of. We have the space in the house- one of the international boys had to go back home in February, so there is a vacancy." Then he looked the boy in the eyes. "It could be useful to help you get used to a school environment, given that you've never had it before. We will want you to sit a couple more papers, too- where you don't have a GCSE- French, Greek, Latin for example. We will need to know how to slot you into the programme. And I will have the music master assess your violin-playing." He looked thoughtful for a moment. "It's workable, for the right boy. Of course, there are lots of bits to sort out but I see no reason why you can't get started this summer term. So long as you are prepared to give it a go, young man, I think we are." With that he stood up, and escorted them back into the anteroom. As they were about to leave, Esther gave Sherlock a rather pointed stare. He'd forgotten something important.

The thirteen year old realised his mistake and turned back to the House Master, to shake his hand. "Thank you, sir."

"You are welcome, young man."

"Um…sir, I _really_ hope that you will consider giving up the smoking. Polonium 210 _is_ radioactive, and sufficient exposure causes genetic mutations leading to cancer."

Goodison smiled. "I will bear that in mind, Holmes. See you in a few weeks."

oOo

John watched his agitated flatmate pacing. "Sherlock, really. I think you need to sit down."

That earned him a filthy glare. "You don't understand, John."

The doctor suppressed a smile. "Actually, I do. I've counselled enough people- friends, family and colleagues- through the process of quitting. It's not impossible. It just feels like it right now."

His flatmate huffed. "Well, the NHS website says that exercise is one way to stop cravings." He gestured at his legs, and resumed pacing.

John pursed his lips. "I think they had something else in mind, like taking up tennis or something. Your pacing is just winding you up even tighter. It's about using proper exercise to release endorphins. You've read the leaflets, you know that."

Sherlock groaned. He'd come to a halt in front of the mantle over the fireplace. He looked at himself in the mirror. His eyes were sunken and lacklustre, his face was flushed. "Just look at _that_ \- I'm a wreck. I can't concentrate on anything. I'm running a low fever. I'm exhausted but I can't sleep. My stomach hurts. I'm both nauseous and constipated. I've got a filthy headache. My chest hurts and I'm coughing. Look at this!" He held his shaking hand up for John to scrutinise. "This is _NOT_ healthy, and if this is what it means to give up smoking, then I'm all for a relapse."

John tried to hide his smirk. In his most patient tone of voice, the one he reserved for the five year olds at the surgery who were in the midst of tantrums, the doctor just chided gently. "It's early days, Sherlock. How long has it been?"

"Six days, seven hours, twenty three minutes and a number of seconds. And every single one of those seconds has been counted, I can assure you. Surely by now I should be feeling better, not worse."

"I know you can do this, Sherlock. You've got a case of 'quitter's flu'. It will pass in another couple of days. You can wait it out. After all, you've managed to beat cocaine withdrawal, so this should be a piece of cake."

His flatmate just moaned again. He wrapped his silk dressing gown around his thin frame, strode back across the living room and sat down on the sofa. He clutched his head in his hands, tangling his fingers into the dark curls and pulling. "This is _worse_ than a cocaine withdrawal. At least that is over quicker. This could take _months_ , John, and I don't have time for it!" There was just the vaguest hint of hysteria in his tone. "I _need_ some. I _need_ some _NOW_."

Without another word, John got up and went into the kitchen returning with a glass of water, which he thrust at the heap of misery that was his flatmate.

The doctor in him had some sympathy with Sherlock's distress and agitation, even though, as someone forced to share his living space the process was proving to be very trying indeed. "You're just going through normal withdrawal. It won't kill you, so stop whining. Drink this; it's one of the D's"

That brought another filthy look from the sofa. " _Whining?_ I am not _whining_ , John. I am suffering!"

John tried again. "Think of something else. You've read it- another of the five D's is distract."

Sherlock sighed, but took the glass, grumbling "it will just make my stomach hurt more. It'll be your own fault if I throw up on you."

John tried to cheer him up. "One of the advantages of this is that you will get your appetite back, and you'll actually be able to taste food properly again."

The space between Sherlock's eyebrows wrinkled. "I'm hypersensitive, remember John? Why would I want to _enhance_ my sense of taste or smell? As revolting as it was when I got started, the smell of cigarette smoke now just sets off a dopamine frenzy. I'm Pavlov's dog. Anyone lights up in the room and I start getting a rush."

When he put his empty glass down on the coffee table, he was still sulking. "It's no use. Without a case to distract me, the only thing I can think about is nicotine, smoking and the whole wonderful mysterious chemical reactions that should be firing up my brain's neurotransmitters. Instead there is nothing…No, I lie, it's worse than nothing. It's the _absence_ of everything that I live and breathe for- mental stimulation, energy, pleasure- all those endorphines and adrenaline. Without a case, smoking is the only thing that keeps me sane."

"You've used nicotine patches for years; why are you saying now that it is impossible? I don't get that."

"I use _both,_ John. I smoke _and_ I use patches. If you think I can give up smoking and just rely on patches, then you don't understand how patches work. They are _slow release_ \- that means they don't actually work to do anything like what smoking does. A cigarette is the most efficient drug delivery system in the world. It crosses the brain-blood barrier and means that you get the full benefit in seven to ten seconds." He rolled up the sleeve of his dressing gown to reveal the two patches, gesturing dismissively. " _This_ abomination drips a tiny dose through continuous osmosis across layers upon layers of epidermis. In short, it's designed to be ineffective background noise. I use a patch simply to keep my nicotine levels topped up to the point where a cigarette can send me into overdrive."

The doctor's patience was beginning to wear a little thin. "Maybe, but those patches won't kill you, whereas smoking will. So, just …I don't know …go _meditate_. Contemplate the statistics of avoidable deaths due to smoking, and try to imagine having to suffer the symptoms of chronic obstructive pulmonary disease. Let that fill your head with reasons not to smoke."

"That doesn't work. It never works. That stupid leaflet said I should beat cravings by going on a 'mini-mental vacation'. Have you ever heard anything so absurd in your life? I'm supposed to visualise myself 'well and happy in a place I cherish'." He snorted in derision "What utter rot! The only acceptable distraction is a crime scene. If I smoked there, Lestrade would shoot me, and Anderson would spend all his time berating me for contaminating the scene, instead of doing his job."

"For someone who's prided himself on his logic, you're not being very logical here. In fact, I'd say you're actually getting quite _emotional_ about it."

Sherlock's glare now could burn holes through sheet metal. "I am _not_ being emotional!" The volume and tone of voice in which the denial was uttered gave John all the proof he needed that his friend was just about to go into meltdown.

"Okaay, let's be scientific. What's in the smoke that you so desperately want to inhale?"

Sherlock was back up, pacing. "There are over 4,000 separate chemical compounds released when a cigarette is smoked, and most of them are toxic if they were to be ingested in sufficient quantities in one go- which of course, they aren't, so that renders the anti-smoking lobby almost apoplectic with rage. Carbon monoxide and nitrate oxides, of course- but you breathe those everyday as a pedestrian in London, so don't blame cigarettes. Then there's hydrogen cyanide. That's the principal ingredient of Zyklon B, a chemical used by Hitler in his mass genocide efforts- but again, in such trace amounts that a single cigarette isn't a matter of life or death. There's now evidence that there are at least three poisonous dinitroaniline pesticides used in tobacco farming that are being ingested through cigarette smoke-flumetralin, pendimethaliin and trifluralin. They are carcinogens, most cause oxidative stress and the last is an endocrine distrupter. Yes, over a lifetime of smoking this stuff accumulates. But…just one cigarette is not going to kill someone."

"Yeah, well, that's the problem isn't it? There is never 'just one' cigarette. The addiction means you just keep going back for more and more. What's the worst chemical ingredient in cigarette smoke?"

"Polonium 210."

"What's that?" John looked confused.

Sherlock waved his hand in dismay at his flatmate's ignorance. "I assumed, _incorrectly_ it would appear, that medical school actually taught you something about the periodic table. No wonder the NHS is staffed by people who could write leaflets talking about 'mini mental vacations' as if it were real medicine."

John had a scale of Sherlockian insults that told him a lot about the mental state of his friend. That one was definitely starting to register in the red zone. Distraction therapy was needed, urgently.

"Okaay, for the mentally deficient amongst us _normal_ people who don't know the four hundredth isotope of the 80th element on the table, explain why I should care about polonium."

This brought Sherlock to a halt. A confused look came over his face. "Number 80 is mercury and it only has seven isotopes." Then he started walking again. "Polonium, Number eighty _four_ on the other hand, has the most number of isotopes of any element, which is thirty three, not four hundred."

John rolled his eyes at the little lecture. "So, what makes it _worse_ than the other stuff in smoke?"

"All thirty three isotopes are radioactive, ranging in atomic weight between 122 and 220. Polonium 210 was used in the Manhattan project- with beryllium, it was a key component of the trigger mechanism for the Americans' "Fat Man" bomb used at Nagasaki. "

John's eyes widened. "Why isn't this better known?" He sounded incredulous. "I mean smokers are actually dragging radioactivity into their lungs?" His disbelief was palpable. "No wonder they make every packet carry a 'smoking kills' warning."

Sherlock just shrugged. "No one can prove that polonium is the guilty party…yet, anyway, but it is known that radioactivity leads to gene mutation- and carcinomas are just mutations, so yes, polonium is the prime suspect. "

John fixed him with an outraged stare. "You claim to be a chemist but you are willing to put that…that _stuff into_ you? I don't get it. How could you?"

"Well, I don't think of it in those terms, do I? Smoking is a means to an end- the adrenaline rush, the stimulation that I need to clear a path through all the sensory input- you don't really understand it, John. it's a case of 'Live today, for tomorrow I may die'. I need to smoke now in order to stay sane under the onslaught of just so much data. It's a form of self-medication."

John narrowed his eyes at the direction this was going. It was as if Sherlock was talking himself back into smoking. "What's the half-life of polonium 210?" he barked.

"138.376 days"

"Well, I don't intend to be there watching you go through chemotherapy when your smoking causes cancer. So, every time you even think of smoking in the future, just calculate the half-life decay of your blessed polonium and work it through mathematically through every single step of decay. If you still feel cravings after that, then just…" he hesitated a moment. "…then just go on a little _mini mental vacation_ exploring the periodic table for another lethal chemical you want to avoid."


	2. Chapter 2

**Summary for the Chapter:**

> Polonium is an extremely toxic element if ingested or breathed in. However, it is relatively harmless otherwise as human skin is sufficient to block alpha particles emitted by the radioactive element. In 2006, Polonium 210 was involved in the most significant radioactive "incident" in London's history.

James Heneghan wrote the mark across the front cover- 55- and scrawled his feedback comment: "Safe topic, but you need to be more ambitious next time". Yet another boringly predictable report, recounting the West Acre boy Mark Thompson's efforts to build an internal combustion motor from scratch. If he had a pound for every similar project he'd seen from his students over the years, he'd be able to afford a more upmarket car than the ancient Renault in his driveway. _What is it about school boys and cars?_

The forty-three year old bachelor was a Master at Harrow College, who specialised in mechanical engineering. It was a core unit for all fourteen year old Removes, alongside Information Technology. Unfortunately, in the 1990s, IT was way more interesting to the boys than the old "nuts and bolts" subject, and he sometimes struggled to get his students to see the relevance of it.

It was going to be a long night. He took a slurp from his coffee mug and reached for the next folder on the pile. This was the written report of the term-long "independent project" that each boy was required to complete. The written report had to explain the challenge presented by the engineering problem they selected, give some history, identify the key issues, and justify their proposed solution at every step of its production. It was designed to test the pupil's ability to do self-directed study; the more thorough the research, the more methodical the approach, the higher the mark. Tomorrow the practical demonstrations of their working models would take place- a ten minute presentation to be delivered by each of the forty-three boys taking the class this term.

Heneghan had a sheet beside him, where he was allocating each of the boys to one of the six masters who had "volunteered" to hear the presentations. Some of them enjoyed the demos- "It's always fun to watch the wheels fall off" was how one of the history masters put it. The three IT masters were also keen- the trend towards robotics driven by simple computer programs made them more interested. And robots did help deflect some of the boys' distain for "grease monkeys" into something more enticing to future engineers. Over time, however, he had come to terms with the fact that very few of his pupils would go onto become qualified engineers- despite the country's crying need for them and the chronic skills shortages that damaged the UK's prospects. He was cherry-picking the best ones he wanted to see himself; he found it too depressing to discover how little of an impact his teaching had on the others. Mark Thompson's rather average work was quickly allocated to Michael Jeffries- the PE instructor was a petrol head who lived for cars.

A sigh escaped him as he picked up the next folder on the pile and saw the name: WSS Holmes. Here was an example of the problem. A boy that every other Harrow master seemed to think was a genius, yet Heneghan had struggled for weeks to keep him interested in the curriculum. "Boring" was the boy's only comment when asked for his opinion of the class work in the second week. He'd kept him back after the session ended to see if he could kindle any spark of enthusiasm.

"Mister McGarry says you are a star pupil in chemistry. Mechanical engineering requires the same kind of problem solving; the two disciplines are closely related. If you're willing to keep an open mind, I think you could enjoy this subject."

The sullen sideways look from the boy suggested otherwise. "Chemistry is not boring. This stuff…" the fourteen year old gestured at the structural diagrams of mechanical objects pinned on the classroom walls, "…well, it's just a means to an end, isn't it?"

Heneghan argued that means and ends were linked- and if Holmes meant to get the most out of Harrow, he had to take the required subjects.

"That's the problem, sir. It's _required_. All the other subjects, I can take an exam or do a test to show that I don't have to waste my time. My other teachers are willing to adjust their teaching so I don't get bored. I'm doing A level and above work in my other subjects, so learning how a…a gear works is just so basic." He fidgeted in his seat.

"Basic? No, that's not fair. To get mechanical engineering right requires mathematics, physics and chemistry, an understanding of materials and how they work, and it's creative, as well. Think of it as scientific problem solving, with a practical result. Design a better mousetrap, and the world will beat a path to your door."

Holmes was looking out the window, with a puzzled frown. "Why would I want to catch a mouse? And why would I want to attract anyone to come to my door?"

Heneghan had just rolled his eyes at the literal interpretation, and sent the boy onto his next class. Looking at Holmes' name on the assignment cover sheet, he sighed and turned over the page to read the title of the boy's independent project.

" _The Design Challenges of an Umbrella Weapon"_

That made the Master's eyes widen. He'd had students in the past who had tried their hand at making a gun or cannon, even a homemade bomb once that he had to stop before it progressed beyond the first stages. "Not socially acceptable, Roberts," had been his advice. "Try something else less likely to end with the police taking an interest in you."

This topic, however, was…unusual, to say the least. Was Holmes taking the mickey? Choosing something frivolous to show he thought the whole subject to be a waste of time? He flipped over to the table of contents, and was surprised to see an outline that promised a completely serious treatment of the subject.

The first paragraph of the introduction explained,

" _There is a serious issue of how law-abiding citizens can be prepared to defend themselves against attack without raising suspicions. Gun and knife control laws that stop a person carrying a concealed weapon mean that it is increasingly difficult for someone to protect themselves against criminals who are not deterred by the laws. My objective is to turn an ordinary harmless object that would be overlooked by an attacker into a defensive weapon capable of incapacitating that attacker. Fortunately, the English weather provides me with an obvious choice- an umbrella that can be used as a weapon_."

Heneghan smiled. He just might find this amusing. The Master wrote a comment in the margin: " _Well done for considering the legal constraints on design ideas_!"

There followed an serious chapter on the history of the umbrella, its origins in ancient times (" _Historians argue whether it was first 'invented' by the Chinese or the Egyptians over three thousand years ago, but most agree that these first versions were designed to keep both sun and rain off of its users. A symbol of wealth and status, these parasols were carried by slaves or servants, if wall and scroll paintings are to be believed.")_

The next section covered the historical evolution of the basic design components of every umbrella- the canopy, ribs and stretchers, the shaft and the runner that opened and shut the umbrella, as well as the evolution of the materials used for each over the millennia (" _The story of the modern umbrella is linked to the Industrial Revolution and the ability of craftsmen like Samuel Fox of Stocksbridge, near Sheffield, to draw steel wire to the quality needed to form the ribs of what we know today as the 'gentlemen's umbrella.")_

Heneghan got up and poured himself another cup of coffee. Like most school teachers, he normally marked papers in a particular way. He knew the grading criteria for this assignment, and went looking for them, which meant a quick scan through all the pages to be sure that the necessary items were present. It was a mechanical process of mental boxes being ticked, and writing grammar and punctuation assessed. If the required elements of research, history, design, materials, specifications and construction processes were laid out and persuasively communicated, with good use of visuals, references and a scientific grounding in mathematics, physics and engineering practicalities, then the points would add up to a high mark.

As he settled back into his desk chair, he found himself reading Holmes' text differently. Chapter Two was all about the evolution of the modern umbrella as a weapon, starting as early as 1838, _"when the Baron Charles de Berenger suggested several ingenious methods for using an umbrella in defence against highwaymen and ruffians."_ The report went on to talk about " _Bartitsu founder EW Barton-Wright's articles in Pearson's Magazine"_ , which used the umbrella as the first line of defence, and how by 1908, the idea had crossed the Atlantic to be taught in Philadelphia.

" _But, all these uses were examples of existing umbrellas being put to a defensive use, rather than a specially designed weapon_." There followed three paragraphs on the "umbrella sword"- where a short rapier like weapon was hidden within the shaft of the umbrella. Heneghan smirked when he read Holmes' comment: " _The effectiveness of such weapons, however, depends on the fencing skills of the user, which for obvious reasons, have declined in the twentieth century. Legal constraints against concealed bladed weapons make this option unacceptable for my purpose."_

Then the next section of the chapter made his eyes widen: a detailed design analysis of the weapon used to kill the Bulgarian Georgi Markov, victim of an "umbrella assassination" at a bus stop on Waterloo Bridge in late August 1978. " _This was a much more challenging design exercise- to develop the ability to propel a pellet with a lethal dose of poison."_ Holmes obviously had an interest in the macabre. Detailed schematic diagrams accompanied the text to demonstrate how compressed air had been used to propel a tiny pellet no larger than a pin head at least three feet. The Master remembered reading about this in the newspapers when he was at school. There had clearly been some investigations since those days which revealed much more about the plot, including how a 'pilot' exercise on the Paris Metro had failed to kill Vladimir Kostov, another Bulgarian dissident, two weeks before Markov was killed.

What fascinated Heneghan was Holme's analysis of the pellet. " _To be effective, the tiny pellet needed to be very small, so as to avoid raising suspicions during an autopsy. The poison, too, needed to be carefully selected so as to mirror natural causes of death. Ricin is not a particularly fast acting poison, and the victim took several days to die. The earlier target Kostov actually survived. So a lethal dose in such a tiny pellet delivery system could not be considered a defensive weapon capable of incapacitating an attacker."_

When the master turned over to the next section, he found Holmes' 'solution'. " _The propellant system used by the Bulgarians is a sound one, and my design has merely taken advantage of the technological improvements to materials design and compression techniques over the past sixteen years."_

The new weapon schematics were impressively detailed. Measurements down to 1.5 millimetres were included, as well as weights and chemical compositions. The weapon was an adaptation of an existing "eight rib manual Gents Tube Frame umbrella with dark-brown hardwood handle" made by Fox Umbrellas of Surrey. There was a reference to an Appendix in the back of the report, to which the Master briefly turned. It was a fully detailed budget that made his eyebrows rise. Holmes must have read enough proper technical design specifications with budget breakdowns to be able to approximate what was required.

The design process was then carefully detailed with a time line worthy of a scientific paper. He spotted a week in which a delay was footnoted. " _Manual operation was necessary, as the automatic version interfered with the trigger mechanism. This set the project back by nine days. Fortunately, Fox Umbrella Company was willing to exchange my original purchase with one that had no automatic opening mechanism."_

By the time he had reached the twentieth page, Heneghan was hooked. The mechanics of the adapted umbrella were explained in detail. Materials changes from the Bulgarian version were carefully noted. The propellant used was much more powerful, so the payload could be heavier. " _With no need to hide the penetration of a 1.3mm pellet, a larger ball bearing of 3mm is used. This can be manufactured to order with surprising ease; my version took a mere six weeks between order and delivery by a well- established Midlands manufacturer who was happy to drill a hole in each hollow ball."_ A page in the Appendix included a photocopy of Holmes' design spec sent to the Midland Bearing Company of Kingswinford, which would have been treated by their ordering department without a thought that it had come from a fourteen year old schoolboy.

Unlike the Bulgarian umbrella, this version of the weapon could fire three pellets. " _I was not obliged to follow the Bulgarians' insistence on using a ball bearing made of platinum and iridium, to ensure that it did not distort on impact and create a suspicious entry wound. This allows a more potent dose of a different sort to be delivered (See below, Section 4.2 Ballistics, and Chapter Five- The Payload)."_

He took a good look at the design of the pellets. Holmes proposed injecting his 3mm ball bearings with poison, then sealing the hole with a wax plug that dissolved at body temperature as described. " _The friction of propulsion and entry into the assailant's body will accelerate the melting process and deliver the poison within moments of penetration."_ It was a perceptive application of science and design to a lethal intent.

The ballistics section included detailed mathematical calculations of the firing trajectories and distances for the weapon.

The final chapter was…scary. As Heneghan read on, he realised that Holmes' love of chemistry might have played a key part in choosing this project. " _I originally thought that polonium 210 would be a suitable poison, but soon realised that obtaining the quantity needed was not easy. Nor, after researching the medical symptoms it induces, did it seem suitable to the task at hand- no matter how lethal its reputation."_ The section went on to give a detailed explanation of why his new "poison of choice" was a form of aconitum- deadly nightshade. There was yet another appendix detailing the biochemistry of alkaloid toxicity and why monkshood had been the classical choice of poisoners for centuries. " _Easily obtainable in my home garden, just one tenth of a grain is sufficient to kill, and an attacker will be seriously incapacitated within moments of being hit. Death takes place anywhere between eight minutes and an hour, leaving time for interrogation. This makes my design more effective as a weapon. As the adage goes, the best defence is a good offence."_

Heneghan wrote the mark – a 95- on the front cover and scrawled a comment beneath.

"I am pleased to see that you now appreciate the challenges of mechanical engineering. A highly unorthodox project, albeit with somewhat suspect ethical motives. You will not be allowed to use real poison in the demonstration- and certainly not with a live target!"

He wrote Holmes' name on the demonstration list for himself. He would make sure to examine the pellets before the umbrella's poison payload could be test fired. _Wouldn't put it past him to have tried it earlier; he seems to take these things very seriously._ He'd tell McGarry to keep an eye on him when the boy was around any toxic substances in the future. Sherlock Holmes was certainly one of the more memorable students he'd ever taught at Harrow. He reached for the next report on the pile.

oOo

 _What an utter shambles._ Mycroft was not a man who needed to shout. The quiet tap of his umbrella on the wooden floor had been enough to silence the cacophony of voices in the room. Assembled in the large meeting room in the Cabinet Office were the best and the brightest minds from the three intelligence services, the Metropolitan Police's counter-terrorism command together with their radiation team, experts from the Health Protection Agency's Centre for Radiation, Chemicals and Environmental Hazards, council officers from Westminster and Camden boroughs, and a senior member of the Crown Prosecution Office.

The post mortem on Alexander Litvinenko had just been read out to the room. The Home Office Senior Pathologist was clear: "Cause of death is now confirmed- poisoning through ingestion of Polonium 210. Unfortunately, the symptoms are notoriously difficult to pin down- and the test results proving its presence only came through seventeen hours before he died. There was _no_ injection or wound site, so this is _not_ a case of Bulgarians wielding umbrellas", the pathologist noted wryly." You will need to look for how a tasteless, odourless but nevertheless lethal element was introduced to his food or drink."

Within hours of a meeting with two Russians in central London, the Russian dissident Litvinenko had started to vomit. Admitted to Barnet General Hospital three days later, his condition deteriorated rapidly, and he was moved for specialist treatment at University College London Hospital thirteen days later. Even before he was moved, MI6 had mobilised a multi-agency taskforce to investigate the possibilities. It had taken the services 22 days to confirm the toxin, but by the time the truth was known, he was already in a coma. He died seventeen hours later.

It was one of Mycroft's personal nightmares. There was something about Polonium 210 that created alarm- unseen, undetectable without specialist equipment- it was the stuff of spy novels and James Bond movies. Unfortunately, in this case, it had proved to be non-fiction.

Mycroft moved to the front of the room, all eyes on him. "We have work to do, ladies and gentlemen. One good thing about Polonium- it leaves evidence behind in the shape of detectable alpha particles. Sites all over London will have to be investigated and contaminated traces identified and removed. There is a public health issue, and it will not be possible to keep this one under wraps."

He added dryly, "thanks to the victim and his wife's bedside interviews, once the truth becomes known there will be a ridiculous amount of media hysteria. There will be scare-mongering and finger pointing, I am sure, about how a radiation threat could go undetected for 22 days, during which time 'countless innocent civilians' could have been exposed. We must have the evidence ready to counter such stupidity. Mister Smithson, best give the official HPA line, please."

The grey haired man stepped forward and turned to address the room. "Whatever the media say, the truth is that the risks are very low. As an alpha-emitter, Polonium 210 represents a radiation hazard only if taken into the body. Alpha particles don't travel far - no more than a few centimetres in air. They are stopped by a sheet of paper or by the dead layer of outer skin on our bodies. Therefore, external exposure is not a concern and it does not represent a risk to human health as long as it remains outside the body. Most traces of it on a person can be eliminated through careful hand-washing and showering. The main risks are to the health care staff at Barnet and UCL hospitals, if they had an open wound themselves, or somehow ingested the victim's bodily fluids. Normal hospital hygiene should have eliminated that risk. So the public message can be reassuring. "

Privately, Mycroft doubted whether the media would be so placated, but he blandly said "it's our responsibility to get that message out while we are pursuing the investigation." His brow furrowed as he went on, "Internationally speaking, things will be more difficult. There is no way that the Home Secretary will be able to deny that Litvinenko was employed by MI6. At that stage, our investigation into the two Russians implicated in his murder will have become an affair of state, rather than a factual exercise. Successful prosecutions are…unlikely."

He gave Charlotte Carter of the CPS a doleful look. "Cases may be brought simply as an exercise of putting pressure on Putin's government. And things could get ugly between us and the Russians." He then turned his attention to Gareth Jenkins, the Met's top officer on the case. "There will demands for public inquiries, and you need to be seen to have done everything by the book, with no loose ends. The widow will make sure that this one stays in the public eye for months." He gave a wan smile. "Not the best place in which to conduct an investigation, but it is what we are left with."

Despite his mild demeanour, Mycroft was inwardly fuming. John Greenway, the current MI6DG,was an idiot. He should have known that Litvinenko would be targeted. And in such a high profile way- an assassination designed to catch the news headlines, carefully orchestrated to embarrass the UK government, at a crucial time just after Blair had announced his intention to resign the premiership. Political infighting within the Labour Party over who should succeed was crippling the image of the government. _Why am I not surprised that they chose_ _now_ _to execute Litvinenko?_

Still, whatever stupidities had led the dissident to meet with Andrei Lugovoi and Dimitri Kovtun, his MI6 handler should have known better than to allow it to go ahead. Litvinenko had been lured to the meeting by Lugovoi, who promised fresh evidence about Spanish links to the Russian mafia. As if that wasn't incentive enough, the Russians had also dangled the prospect of something about the links between Putin's FSB and the death of the St Petersburg journalist, Anna Politkovskya, last month.

It was a classic entrapment exercise, and the proffered intelligence was simply too good to be true. Mycroft would make sure that his MI6 handler would be dealt with. And it was time to think of a new replacement for Greenway; perhaps Elizabeth Ffoukes would finally get the chance to take the top position for which she was eminently suited. Mycroft respected her talents and her discretion- attributes the current incumbent lacked. There might be one silver lining in this dark cloud of polonium.

He continued, "We have four hours before the COBRA meeting, and one week before the Home Secretary needs to make a statement to Parliament. We need to use that time wisely." His Security Liaison Service was playing the co-ordinating role. "My PA will give you your assignments. Now that we know exactly what we are looking for, the forensic evidence will be simple to acquire." He gestured with his umbrella over his shoulder at the evidence board. "The timeline of his movements on the 1st of November is clear. Traces of polonium 210 are likely to be found at key points in his route that day- some of which will have been left by his assassins. We suspect the two so-called dissidents he met with at the Millennium Hotel are the culprits, so check the planes they arrived on and departed on, and where they went during their stay in this country. Polonium 210 has a half-life of just over one hundred and thirty eight days, so plenty of time to track this one down before the evidence…disappears."

Murmurs from the room threatened to become conversations. Mycroft needed to get them to focus. He coughed discretely, and the talking stopped. "You have two hours to prepare your papers for circulation to COBRA. I suggest you get started." He shouldered his umbrella and walked out.


	3. Chapter 3

**Summary for the Chapter:**

> Because the element does not emit gamma rays (unlike most radioactive materials) it is difficult to detect, and no hospitals or emergency services have equipment that can trace its alpha particles. The death of Litvinenko was the first occasion when Polonium-210 was confirmed as a murder weapon. The 'fall out', in terms of contaminated relations between the United Kingdom and the Russian Federation, however, lasted far longer than the polonium's own half-life.

The DI was standing outside Sherlock's flat in Montague Street. He'd just rung the bell, but rather than the sound of the electronic door catch being released, the intercom box beside the door had crackled into life. "What do you want?" The sound quality was so poor that Lestrade couldn't tell if Sherlock knew it was him, or whether he was just indulging in his typically rude reaction to someone ringing a doorbell.

"Let me in, Holmes. It's Lestrade- I've got a case for you."

"Tell me what it is. I can't be bothered unless it's really interesting."

Greg tried to control his temper. "Let me in."

When there was no response, he sighed and bent over to the intercom box, in the hope that it would carry the message. "Your phone's been cut off again- and your mobile service says your number's been discontinued. Don't make me do this in the street, Holmes."

There was a tone of pleading in Lestrade's voice. He knew it was there, but he couldn't help it. He needed Sherlock's ability to cut through all the clutter to find the truth. "This one's complicated. It's a crime that hasn't been committed yet, but the 'victim' is absolutely sure it's going to happen."

The electronic door lock released and Lestrade pushed it open, slipping in and then taking the stairs two at a time up to the third floor. When he got there, out of breath and panting, Sherlock's door was ajar, so he went in. A quick glance around the bedsit showed it to be in its usual state of squalor- piles of newspapers and books, a full ash tray. When he turned to the left, he saw the younger man standing bare footed at the tiny kitchenette's sink, wearing only a pair of pyjama bottoms. He was putting water into the kettle with one hand, while fishing in the drawer for a teaspoon. The open jar of instant coffee was waiting.

"Want a cup?"

"Sherlock, it's after noon. Are you just getting up?"

"Irrelevant to the question I just asked, Detective Inspector. You know I hate repeating myself."

Lestrade sighed. "Yeah, I'll have one, if you can find a clean cup that isn't loaded with bacteria."

"I am not currently running any experiments in coffee cups."

Greg pushed aside some newspapers on the sofa and sat down. There was a dent in the cushions that still felt warm; he assumed that the younger man couldn't be bothered to open it out to the sofa bed, and had been asleep when the door buzzer went off. "I wasn't talking about that; it's just your housekeeping skills leave something to be desired."

The kettle boiled and clicked off. Sherlock filled two mugs and put a lump of sugar into one, stirring vigorously. "Who's about to become a victim?"

"His name is Boris Berezovsky. A Russian oligarch. Rich as Croesus, but got in trouble with the powers that be in Moscow, so he fled here."

Sherlock snorted. "Joined the crowd then, did he? And what marks him out as special? Half of Belgravia's Russians assume they are on a hit list somewhere after Litvinenko last year." He handed Greg the unsweetened coffee.

The DI looked into the mug. "I suppose it is too much to ask for a little bit of milk?"

"Fridge space is currently taken up with experimental samples. I don't think milk kept in there would pass your hygiene test."

Greg grimaced as he took his first sip of the strong coffee. "What's been keeping you up all night that you have to sleep half the day?"

"None of your business, Detective Inspector. Say your piece, or leave."

 _God, his social skills are getting even worse._ "Boris keeps a contingent of bodyguards worthy of a man worth a billion plus. But, he's been getting death threats, and this time he thinks they need to be taken seriously."

Sherlock was now standing at the window looking out over Montague Street. "Tell me something new. Every Russian worth anything these days gets death threats. Why take him seriously now?"

"He's linked to Litvinenko."

That made the younger man turn from the window and look at Greg. "How?"

The Di knocked back another swallow of the bitter black coffee. "Lots of ways. Let's start with the fact that when he was in Russia, someone tried to blow him up with a car bomb. Killed the driver, but Boris survived. That was 1994. The FSB officer who investigated was none other than… Alexander Litvinenko. Then Boris and his rich mates got together in Davos and decided to put millions into the presidential campaign of Yeltsin. He got his reward in the shape of influence in the Kremlin. Trouble was, he made enemies along the way- some in Chechnya, some in Moscow."

Greg decided he'd had enough of the coffee; any more of it and he'd end up tap-dancing on the ceiling all night from caffeine overdose. "Now fast forward to 1998. Litvinenko resigns from the FSB and goes public, saying that he's the one who was ordered to kill Berezovsky. He ends up in jail for it, and Boris gets attacked instead in the Russian courts, with his business interests getting slammed. He backs Putin as Yeltsin's successor- the two used to be 'friends' apparently. But as soon as Putin's in power, he turns on Berezovksy. Eventually the heat gets too much and in 2000, Boris is on a business trip and decides not to go back to Russia- ever. Once Litvinenko gets out of jail, he bolts for London, too. The two meet up and join forces to launch the International Council for Civil Liberties, whose avowed purpose is a 'bloodless revolution' to overturn Putin. And you know what happened to Litvinenko seven months ago."

Sherlock was smiling now. "Lestrade, I didn't know that counter-intelligence interested you. This sounds more like something that my brother would be talking to me about, not you."

"Yeah, well, I can't say the topic interested me before last night, but the guy spent two and half hours last night bending my ear."

"Why _you_?"

"Because I had the misfortune of sitting next to him last night at a charity gala organised by Louise. She does this kind of stuff- PR and events- to bring money together with worthy causes. He's got money, so she invited him. I get to sit on the top table because I'm Mister Louise. So, he writes his cheque as soon as he sits down, and then when he finds out I'm a police officer, proceeds to tell me his life story." He put the coffee mug down on the floor beside a pile of old newspapers. "And then the guy calls me up this morning and tells me he'll add another couple of zeros onto that cheque to the charity if I can do something. Louise now says I have to do something."

Sherlock chuckled. "Sounds like he knows how to play you."

Lestrade grimaced. "The things I do to stay happily married." Sherlock raised an eyebrow, but before he could pronounce yet another one of his doom-laden comments of the state of his marriage, Greg cut him off. "I can't do a damn thing until he's actually been killed- police protocol and all that- but maybe you could take a look for me? Go talk to him. See if he's got some reason to be worried?"

"Get you off the hook, you mean."

Lestrade had hoped that he wasn't being so transparent. "Yeah, actually. There's nothing the Met can do. Berezovsky isn't on SO6's list. I mean, if we put every rich asylum refugee in London on the list, the budget would be astronomical. He's got his own guards in any case. My guess is that he's certainly on the radar of the Security Services, but…well, you've got better connections there than I do."

"Hmm. Leave it with me."

And Greg did just that.

A week later, someone else in the Met made an arrest at the Hilton Park Hotel of a suspect travelling with a child. Two days later, the man was deported to Russia. Four days after that, Boris Berezovsky was advised to leave the country for a few days, for his own protection. When he returned, Berezovsky gave an interview to the BBC in which he thanked "MI5 and MI6 for their help", adding "I have been asked by the police not to go into detail about the assassination attempt and therefore I will not do so." The Russian could not resist adding, however, that he had "total confidence in both the British police and the British courts. It is a joy to live in a country where the individual citizen's rights are so well-protected."

oOo

John sighed. Whatever he had been expecting from the evening, it had not involved being referee in another skirmish in the Holmes v. Holmes conflict. He'd been sitting at his kitchen table, watching Mary prepare their pasta supper when his phone had gone off.

**18.16 Something interesting- want to join me? Big Brother won't like it. Don't care. SH**

"Why does he put his initials at the end of the text? Doesn't he realise you know the number?" Mary was reading over his shoulder.

"Just a habit of his." John was seriously considering the proposition.

"Go on. You know you want to." She gave him a kiss on his ear. "My pasta is not that great an incentive. I'll watch another episode of the rom-com box set you loathe. Just take care; tell him I want my fiancé back intact."

He looked at her, loving her for the way she had accepted the reappearance of the consulting detective into John's life. Not that they'd had many adventures. Sherlock rarely texted; only a handful of cases since his return two months ago. Always at night, never during John's working hours.

**18.23 Do I need to bring anything?**

It was an oblique reference to whether John should bring his gun. When Sherlock had returned, John had taken it out of the locked box where it had sat for two years and cleaned it.

**18.24 No- unless you have an insect repellent effective against brother. SH**

Almost forty minutes later, John turned up at Baker Street, only to find a government car parked outside. He let himself in to the flat with the key that Sherlock had insisted on giving him when he returned, and climbed the seventeen steps.

When he walked into the living room, the two brothers were in one of their staring matches. Mycroft was in the chrome and leather chair, Sherlock was standing by the table. _If looks could kill._ John wasn't sure if Sherlock would have died faster than Mycroft; both Holmes seemed to be livid, yet silent.

He sighed. "Don't mind me. I'll just get some coffee on, shall I?" He got the kettle on and prepared three mugs. Then the silent stalemate was broken.

"No, Sherlock. You can't go. Your presence is not welcome there. The Thames Police have not _invited_ you." Mycroft's tone was firm.

"How very convenient." Sherlock's reply was scathing. "Why don't you just admit it? Between the Thames Valley Police and MI5, there isn't a chance that the real truth about Berezovsky is going to come out, but you're counting on that."

When John delivered one mug to the consulting detective, he spotted the Evening Standard newspaper page on Sherlock's tablet. The younger Holmes glared at the older Holmes, and stabbed his index finger at the headline _**Russian Oligarch Hangs Himself**_. "And since when do you let the media conduct the post-mortem?"

John handed the other mug to Mycroft, who was looking a little like he needed it. "Thank you, John. It is likely to be a long night. Sherlock, apparently the police found Berezovsky hanging by his neck in his bathroom. Neither Five nor Six have any reason to think that this is not what it appears to be. The man was ruined. He has been depressed for weeks, according to his family, who have been expecting something like this."

Sherlock scowled at his coffee. "As if a hanging can't be faked? And, you don't find it suspicious that his son-in-law has already posted the fact that the man is dead on Facebook, saying it is suicide?"

"That is not a matter for you." Mycroft put on his sternest face, as if hoping it would be enough. "At the risk of repeating myself, need I remind you that you have not been _invited_? You will _cease and desist_ this…interest of yours. You are not to get involved."

"Not good enough." Sherlock took one sip of the scalding coffee, grimaced and set it aside to cool. Then he resumed pacing.

Mycroft tried again. "Just leave it to the experts this time, brother mine. The last time...generated rather a lot of publicity and unfortunate consequences."

Sherlock rolled his eyes. "Oh yes, six years ago you and Putin played retaliation games." He put on a thick Russian accent- "We're deporting four of your diplomats because you've just done the same to us." Then he mimicked his brother's voice perfectly, "Yes, Foreign Secretary, I regret to say the Russians have closed the British Council because it's a spy agency."

Mycroft glowered at him. "That was in response to the Litvinenko case, not your subsequent interference in the assassination attempt made against Berezovsky."

"Hah! You're the one who says the universe is rarely so lazy as to allow coincidence. Odd that the expulsions happened less than a month after I managed to thwart the Russians' plans against Berezovsky. 'Balance of probabilities', brother, as you are always saying to me. And you know as well as I do that the cases are linked. Although you did a better job six years ago at keeping Polonium 210 out of the press that time."

"Enough said about that, brother mine." Mycroft pointedly looked in John's direction.

The doctor shrugged. "Don't mind me, Mycroft. My security clearance isn't high enough even to be in the room with you. So, just ignore me." He frowned at Sherlock's pacing. "He usually does."

That earned him a small wry smile. "He ignores _everyone_ , John; don't take it personally." Mycroft stood up. then picked up his umbrella and coat. "But you will not ignore me this time, Sherlock. If you try to get involved, you will be stopped." It was quietly said, but in a tone that was used to being obeyed.

Despite that warning, John found himself accompanying Sherlock ninety minutes later, on a taxi ride to Berezovsky's home near Ascot. Just getting that far had been an exercise in subterfuge. Sherlock had changed cabs three times, and John knew that the last one would be well out of CCTV range. At Sherlock's request, the last taxi dropped them a quarter of a mile from their destination.

As he marched double-time to keep up with the long strides of the taller man, John wondered whether Mycroft really thought Sherlock would comply with his orders. As the pair ducked behind garden fences and skirted wooded areas, he started to worry what would happen if they did get inside the crime scene.

Sherlock was up and over the nearly six feet high brick wall around the back of a house before John had turned the corner.

"Sherlock!" This was uttered in the loudest stage whisper John thought he could get away with. A pale face looked back over the wall at him. "I could do with some help here." There was a sigh, and then a pair of arms reached over, giving John the leverage he needed to scale the wall. He landed in a flower bed.

The security light overlooking the back patio was on, but the doctor realised that the people inside the house were not really paying attention. There seemed to be quite a crowd.

Sherlock ignored them and moved to a side door into the garage. He crouched down and was busy picking the lock by the time John caught up to him.

"I'm not sure breaking into a house full of police is a rational thing to do."

"I don't care." In a swirl of coat, Sherlock was across the empty garage and in the house before John could reply.

John was surprised at the number of people in the living room. He was used to a MET Murder Investigation Team's work, where Lestrade generally tried to limit the numbers of people on a crime scene, something that John took as a nod to the fact that hordes of unfamiliar faces tended to make Sherlock even more obnoxious than normal, a defence mechanism to deal with his social anxiety.

The place was in an uproar, with CS Examiners bagging and tagging samples. Sherlock just pushed past them, until a uniformed police officer spotted him.

" _Oi!-_ Just who the hell are you and what are you doing here?"

Sherlock walked right past him as if he didn't exist.

"If you're some bloody journalist, I'll have you arrested."

The officer was reaching to grab Sherlock from behind when Mycroft's voice cut across the room. "Clear the room _now._ " It wasn't particularly loud, but the authority in the tone of voice had more effect than mere volume would have. Every eye except Sherlock's turned to look at Mycroft and conversation stopped. The police officer's hand stopped in mid-reach and Sherlock just went on, the only person ignoring Mycroft's order.

John watched as the Senior Thames Valley DCI in the room started to ask- he could actually see the guy's mouth start to form the word _who_ when he was taken aside by a suited man who whispered something into his ear. Mycroft gave him a stern look. "No more than ten minutes should do; thank you." The DCI's eyes widened, and then he said in a loud voice, "You heard the man- everybody _OUT_!"

"With the exception of the first officer to arrive on the scene. He will be useful." This was said by Sherlock over his shoulder as he made his way down the hall towards the bedroom.

Mycroft was politeness personified. "PC Campbell, would you be so kind as to stay behind?"

By the time John caught up with Sherlock, he was in the bathroom off the master bedroom, looking at the obviously empty room. He was in the last stages of pulling on a pair of sterile latex gloves. "They've removed the body." He sounded petulant, like a child who'd been deprived of a favourite toy.

Mycroft rolled his eyes in exasperation. "Obviously. The post mortem could tell us something important."

Sherlock's baritone was almost a growl. "I would have learned more by seeing it _in situ_."

The elder Holmes reached into his pocket. "Then lucky for you, I had the police photographer send me the first images."

Sherlock snatched his brother's phone and looked at it, then at the bathroom floor. "John, would you play dead for me?"

The doctor sighed. "Where?" It was a rather weary sigh. He'd done this before in the absence of a corpse.

"Face down, on your right cheek." Sherlock was looking at the photo on the phone. "Feet toward the basin, head toward the door. Crumpled up, one leg under you."

John got down on the floor in a rough approximation of Sherlock's instructions.

"Luckily, you are almost the same height as Berezovsky." The consulting detective turned his attention to the piece of black cloth hanging on the rail. "You said, he was found hanging. Who cut him down before this was taken?" He directed this question at PC Campbell, who couldn't have been over twenty five, who was standing rather awkwardly in the bedroom.

"Uh, yes…I mean, no- the body guard cut him down. The scarf, half of it's that bit still on the rail, the other half was on his neck where he fell onto the floor. It's been bagged. We're waiting for the CS Examiner to remove the shower rail with the scarf attached."

Mycroft stepped aside to let the PC look into the bathroom, which was rather cramped, what with Sherlock standing between the toilet and the basin, and John crumpled on the floor.

"Don't move, John." Sherlock was glancing to and from the rail to the floor. He fired another question at the PC. "Did the bodyguard say which way the body was facing when it was hanging?"

"Not that I heard; he just said he cut him down to see if he could give him the kiss of life."

Sherlock pulled out his pocket magnifier, and jumped up onto the toilet seat, to examine a splotch on the ceiling. "You found a fingerprint in an unexpected location." It was just over the shower rail. "Not his." It wasn't a question, but a statement. "And it won't match the maid's prints either, although I wouldn't rule out the bodyguard's."

He stepped down and shot a meaningful look at his brother.

"Sherlock, the room is covered in fingerprints. It will take time to eliminate those that one would expect to be there, and to run those that have no apparent reason to be here." Mycroft was frowning.

Sherlock was looking at the photo on Mycroft's phone. "But, you do see the anomalies, Mycroft. Interesting that he was naked. Not clothed." He turned to the PC. "Were there clothes on the floor or hung on the hook? Most suicides by hanging choose to do so fully clothed. It's more dignified. Or was he about to jump in the shower when he suddenly decided to top himself?" Sherlock's incredulity was clear.

Campbell paled a bit. "Um, no clothes in the room; just pyjamas and a dressing gown on the bed. They've already been bagged, too."

Sherlock was now crouched over the fingerprint powder on the edge of the bath. He directed another comment over his shoulder at Mycroft. "Since losing the law suit against Abramovich last year, Berezovsky was broke. He had to sell all of his assets, and stand down his security. So he was a walking target. He must have known it. This is his ex-wife's house- so no special protection measures in place. The bodyguard was hers, not his. No video, no panic alarms; this place is an engraved invitation to an assassin."

"There is evidence, Sherlock, that this was a suicide. Please explain, Constable."

The young officer cleared his throat a little nervously. "Um, prescription antidepressant drugs were on the bedside table. Been removed for testing, but there is nothing to suggest that they aren't what they are supposed to be. The bodyguard said that Berezovsky had been seriously depressed- something his ex-wife, daughter and son have all confirmed, including the fact that he spoke about killing himself several times over the past two weeks."

Sherlock wasn't placated; he didn't stop his examination of the fingerprints on the bath edge, just said, "What's the bodyguard's name?"

The PC looked at his notebook: "Avi Namava."

That made Sherlock stand up and look at his brother, who was now wearing a rather pained expression. The younger man clicked shut his pocket magnifier. "An Israeli? Formerly with counter-terrorism, now working for the private company SQR ? And you _believe_ him? He _discovered_ the body. He's _paid_ to protect the man from an assassin, so if he can blame it on a suicide, then that's him and his company in the clear."

John stirred. "Do I need to stay here? It's a bit cold on the tiled floor."

"Stay right where you are John. It's crucial." Sherlock stepped over the doctor, and stood in the doorway, looking in. "Mycroft, this is nothing short of ridiculous."

He looked at the Constable, and then back at Mycroft, before turning to point at where John was lying. "Assume the body was hanging. If the body guard did cut him down, then the dead body would fall _inside_ the bath, not out. So, the body guard moved the body- a lot. If it was ever hanging in the first place, which I am beginning to doubt." He flapped the end of the scarf hanging on the rail. "Check the scarf around his neck- it's been cut alright, but this end isn't frayed at all or torn- and with the dead weight of a body on it, then it would certainly have ripped the last threads as he was cut down."

The consulting detective was now skewering his brother with a look. "You don't have to tell me that there wasn't a note; I _know_ there wasn't one. And if none of that is convincing, take a look at the photo." He thrust the phone back at Mycroft. " _Brother mine,_ even you can see that Boris's face is almost purple. Gravity means a hanged man's blood will pool lower down once the heart stops pumping, leaving him pale. I don't even need to see the body- the ligature marks will not be consistent with a hanging- more like a garrotte, wouldn't you say?" This was said rather pointedly with some heat.

Mycroft's face was set. "Perhaps. It's for the pathologist to make that assessment. And the Thames Police investigation will consider whether there is sufficient cause to assume he was murdered, rather than a suicide. That's what they are paid to do. As I said before, _you_ are not to get involved."

The three piece suited man looked down at John on the floor. "Doctor Watson, you can get up now. I think my brother is done now with his little party piece." Mycroft was not hiding his irritation now.

Mycroft escorted them out of the house, and the crowd of police and forensic staff flowed back in behind them. When they got to the anonymous black car, Mycroft pointedly suggested that John ride in the passenger seat next to the driver. On the way back up the M3, the tinted privacy screen was up, but even that did not completely stop the sound of voices raised in anger. At one point, the driver looked in the rear view mirror with concern at the noise.

"Ever hear him shout before?"

The driver re-focused his eyes determinedly on the road ahead. "Not my place to say, sir."

When the car arrived back at Baker Street, the passenger side rear door was thrown open before the car had come to a complete halt. Sherlock was out of the car and in through the door to 221b before John got his seatbelt off. Once out, the doctor looked in the still open door to the backseat where Mycroft's face was sphinx-like, set cold stone. Then the man roused himself and with one of his obviously manufactured smiles said politely, "Would you like a lift home, Doctor Watson? I am sure your wife will be relieved to see you back in one piece, none the worse for wear after this little misadventure."

"Ah, no thanks, Mycroft. I'll make my own way, later." John shut the door and went in, noticing that Sherlock had left the front door ajar. _How does he know I would follow him in?_

When he got into the living room, Sherlock was sitting in his chair, facing the cold and empty fireplace. "Sorry, John, for wasting your time tonight."

"Well, impersonating a corpse is not exactly what I had in mind when I answered your text." He was trying to inject some levity into his tone. "But, it had some advantages- kept my head down when the two Holmes brothers were blasting away at each other."

That was one of the things that bothered John the most about the evening. Over the past two months, he'd talked himself into thinking that the enmity between the two brothers that featured in the run-up to the roof-top at Bart's was all part of the 'plan'- manufactured as a smoke screen. But, tonight suggested otherwise; there were still 'issues' between them, clearly. Since his return, Sherlock had been quieter, more guarded, almost sombre. Perhaps it was that John was no longer around him to spot the signs that used to tell him the man's mood. _He's changed._ But no sooner had he thought that, he realised that he had also changed, so who was he to criticise? The reasons which had first drawn him to Sherlock- the shared danger, the adrenaline rush and the thrill- were no longer the main draw. He _worried_ more about Sherlock now.

John tried again. "Well, better luck next time. Not every case is either as interesting as it first seems, or solvable."

"Actually, this one is both. But, I have been told that it is 'off limits'."

"What will happen?" John was curious.

"Oh, in eight or nine months an inquest will be held. The investigation will not reveal anything _conclusive_ because it is politically inconvenient for it to come to any other conclusion. An open verdict will be the best the relatives can hope for, if it isn't ruled a suicide. My brother will have stage managed this one to perfection." He sounded bitter. "Unfortunately, John, I am no longer a free agent. A price I apparently have to pay for returning from the dead."

"Well, I for one am glad that you're back, whatever price you have to pay."

Sherlock resumed his staring into the empty fireplace, as John collected the coffee cups and put them in the kitchen sink for Mrs Hudson to deal with tomorrow.

"Well, I'm off then."

Sherlock's only reply was a sigh.

**Notes for the Chapter:**

> The events and crime scene description are REAL- taken from the inquest that pronounced an open verdict on 27 March 2014. Perhaps Sherlock found a way to influence the one key witness, who managed to convince the Coroner, "against my initial conclusions", that there was reasonable doubt about a suicide verdict.

**Author's Note:**

> Author's Note: To all you smokers out there, I'm not going to apologise. My mum died of COPD this year, and my sister has also got it. Both smoked. Just stop now.
> 
> * At Harrow, the 800 plus boys live in one of twelve houses, and the masters of each house have the deciding vote on admissions. Bradbys is one of the smaller houses, home to seventy boys across the five years that most students are at the school. First year boys- usually 13 years old- are called "Shells". The next year is called "Remove", the next is the more conventional "fifth form", followed by the final "sixth form" years.


End file.
